Pneumatic hammer.



W. F. SCHMIDT.A 'PNEUMATIG HAMMER.4 APPLIUATIO'N H LBD Nov. 1, 1897.

Patented J all. 26, 1915.

I "(rTED s'rn"riasn P Afrn` union.

WILLIAM I". SCHMIDT', or ST. LOUIS, MISSOURI, ,Assioma BY-MESN ASSIGNMENTS, 'ro cnrcaeo PNEUMATIC Toon company, Acoaronarron or nnwennsnr.

PNEUMn'rrc HAMMER.

ll,i26,096.

Application filed Novembelr 1*, 1897. Serial No. 657l046.

To all 'whom it may concern.'

Be it known that I, WILLIAM F. SCHMIDT, a citizen of the United States, residing at the city of St. Louis, in` the State of Mis- .5 souri, have invented a certainnew and useful vImprovement in Pneumatic Hammers, of which the .following is a description, reference being hadto the accompanying drawings, forming part of this specifica? tion. Y

. My invention relates to that class of pneumatic hand tools in which the reciprocating piston of a direct acting engine, operated by compressed air, is employed as a a chisel or other Working tool, and it is the object .of my invention to simplify and increase the eiliciency of this class of tools; all as hereinafter more fully explainedand particularly pointed out in my claims. III the accompanying drawings Figure 1 represents a longitudinal vertical section of my new tool; Fig. 2 a horizontal section on the line 2 2 of Fig. 1; Fig. 3 a vertical cross-'section through the valve chamber,l on the line 3-3'of Fig. l, with the valve in l'ower position; and Fig. 4 a similarA view with the valve in upper position.

The same letters of reference are used to indicate identical parts in all the views.

The body of the tool consists of an outer` Acasing A having a tapering nose B at its front end, and an inner cylinder C snugly, fitting within the casing A and containing the piston chamber within which recipro-V cates the piston D. The front end of the cylinder C is open and communicates with the central'tool-receiving bore lextending forward through the tapered front end of the casing A. This toollreceiving bore has driven into it a bushing or sleeve E within which lits the round shank of the chisel or other working tool F, the extreme rear endv of the shank of such tool projecting into the front end of the piston 4chamber in position to be struck by the front end of the piston at the end of its forward stroke. At .the forward end of its rounded portion the shank of the tool F is slightly enlarged, forming a shoulder which lits against the front end of the sleeve E when the' tool is i n position. The rear end o the cylinder C is y closed by the valve block G which 1s circular' iii, cross-'SQQOB and fits Snugly Wlhll" .the

-Spe'cation o I'etters Patent.

hammer to deliver blows upon the shank of Patented aan. ae, reis.

end of the cylinder C. This .v alve block isl held in place by a cylindrical nut H screwed into the rear end of the casing A and abutting against the rear side of the valve block. The .valve block has formed integral with and extending rearwardly from it a central tube l whose bore is closed at-its extreme rear end by a screw plug J. Fitting upon this tube, between .it and the .surrounding nut H, is a forward cylindrical extension K of the handle L of the tool. The handle is held from displacement by means of a screw M passing through a threaded hole in the vnut H and projecting at its inner end into a longitudinal recess in the extension K of the handle,.this connection permitting slight longitudinal movement of the handle upon the tube l. The handle L is provided with an inlet opening N, interiorly threaded atv its outer end to receive the nipple of the flexible hose through which compressed air or other motive fluid is conveyed to the tool, and communicating at its reduced inner end with an annular groove a formed in the inner surfe ce of the central bore of the handle surrounding' the tube I. The latter is provided with ports a which registerwith this groove in the handle when the latter is pressed 'forward to the position shown in the drawings, thus permitting the motive fluid to enter the tube l. A longitudinal passageV O formed in the cylindrical extension K of4 the handle communicates' at its rear end with the inner end of the inlet port N, .v and at its .forward end opens into the anl nular space P surrounding the tube I' within the cylindrical nut H at the .forward end of the extension Kr By means of this pas# sage O when themotivejluid is admitted tothe inlet port N it will pass at once to the annular chamber P, and there acting upon the front end of the cylindrical eXten-. sion K of the handle 'force the latter rearward, if it has previously been restingv in forward position, or serve to hold it in rearward position if already in such position. Communication between the inlet ort N and interior of the tube I will thus e cut off, and can onlyv be' openedby pressing the handle forward against theresistance of the tool the handle is pressed forward hold the chisel or other working tool 'up to its work, 'so that during such' time the motive fluid will' be.' t0'. the interi@ @if the m los v emotive fluid in the chamber l. In using the'.

tube l, but as soon as pressure upon the handle is relieved it will be forced rearward and the supply of motive fluid cut off.

The interior of the tube I communicates at its forward end by a'port b with the interior of the valve chamber in the block Gr,

- in which chamber' is located the piston lll valve Q. having heads at its opposite ends, and a middle flange, as is common in tools ot' this4 character. A passage R, Fi l, leads forward from the upper end o the valve chamber and opens into the piston chamber by two ports R R, while a corresponding passa e S leads forward from the lower end of the valve chamber and opens into the piston chamber by tw'o ports S S. The piston D is provided near its rear end with an annular groove c which, when the piston is at its movement, establishes communication between the port S and a port@ of an exhaust passage d extending forward through the wall of the cylinder to the common exhaust T, and near its forward `end is provided with a second groove e which, as the piston approaches its rearward limit ofv movement, establishes communication between the port R and a second exhaust port f opening into the passage d. ports T and T open through the right hand wall of the valve chamber, Figs. 1, 3,

and Il, and communicate with the common exhaust port T. A port U opening from the opposite side of the valve chamber'communicates with the frontend of a passage U leading to the extreme forward end vof the piston chamber, shown in Fig. 2. A port V opens through the forward side of the valve chamber and communicates with about the same the rear end of the piston chamber.

Under the foregoing construction of the parts the operation is as follows: With the valve Q in the position shown in Figs. 1 and 3 the live airinlet b will be in communication 'across the valve chamber with the port U and passage U leading to the front end of the piston chamber, Fig. 3, while the inlet port V at the rear end of the piston chamber will be in communicationnwith the exhaust port T', the piston being thus free to move rearward under the action of the motive fluid' admitted to the front end -of the piston chamber throughl the passage U. As the piston moves rearward and nears the end of its stroke the. groove e will place the exhaust port f in communication with the port R and passage R leading tothe upper end of the valve chamber, thereb ermitting the escape of the live air whic as driven the valve downward, and` at time 'the 'front end of the pistonwill pass rearward of anduncover the port S at the front end of the passage S leading to theI lower ,end ofl the valve ber, chamber, with the exhaust port T, as shown 1ri'1=l-.Fig.fl, thereby 'permitting the escape of .the piston, to drive it forward forward limit of-` Two and that when pressure upon the piston chamber be thus admitted to the lower end of the valve chamber, and the valve be moved to its upper position, Fig. il. This shifting of the valve to upper position will place the passage U and port U leading to the front end of the piston chamin communication, across the valve th'live air from thefront end of the piston chamber, and at lthe same time theu inlet ,port -b will be ,placed in communication, across the valve chamber,- with the port V leading into the rear end of the piston chamber, and live air be thus admitted in rear of again.l As thepiston approaches its forward limit of movement the annular groove c at its rear end will place the exhaust port d in communication with the port S of the passage S leading to the lower end of the valve chamber, thus permitting the escape of the live air from beneath the valve, while at the Same time the extreme rear end of the piston will have passed forward of. and uncovered the port R of the passage R leading to the upper end ofthe valve chamber, thereby7 admitting live air from the rear end of the piston chamber to the upper end of the valve chamber, to. drive the valve downward again.

In the manner and by the means thus described the movements of the valve serve to alternately vadmit and exhaust the motive Huidat the opposite ends of the piston chamber, while the movements of the piston likewise serve to alternately admit and exhaust the motive iiuid at the opposite ends of the valve chamber, to cause the' mutual reciprocation of the piston and valve.

' The valve block G has a central circular boss formed upon its forward side which is adapted to enter a corresponding recess in the rear end of the piston as the latter approaches the rear end of its stroke, to cause the air confined in the annular space around said boss to cushion the piston at the rear end -ofits stroke and prevent its'striking the valve block. p

It will be understood from the forego' description that when the working toolmF is placed in pos'tion and the machine pressedXto its work b means-of its handle L the motive liuid will be admitted to the valve chamber and piston chamber and the piston caused to rapidly reciprocate and deliver a. blow to the shank of the working tool at the end of each of its forward strokes, the handle L is withdrawn'the operation of the tool will automatically cease. It will lalso be understood that the shank of the chisel or working tool F, fitting Within the tool-reivt boreinthefrontend ofthe 1:; A,i

piston forms part of the end wallr of meaoee chamber against which the motive fluid admitted to the front end of said chamber acts in driving the piston rearward. By so em' ploying the, shank. of the working tool the means intermediate the shank of the working. to'ol and the front end of the piston chamber, heretofore employed for closing the latter, may be'dispensed with, and the construction of the tool thereby to that ex.-

-tent simplified and cheafened. Furtheri follows that if. the working. tool be removed or displaced from position the front end of the piston chamber will be. left open to the outer air, so thatthe motive uid admitted to it can not drive the piston rearward. It

"therefore results that the operation. of the supplly passage. 4 3. n

machine will automatically cease if the working tool be at any time displaced from position, even though.the throttle-valve of the tool remain open.

Having thus fully described my invention, 'I claim:

. l. In a pneumatic hammer, the-combination of a cylinder, a piston 'arranged to reciprocate therein, a valve located at the rear end of the cylinder for distributing the. v uid pressure to and from opposite en s of the cylinder, `a valve box for such tool having an extension provided with a supply passage communicating with the valve, and amovable member adapted to be connected with the source of supply and provided with a portion adapted to reciprocate upon said extension and to thereby govern its supply pessac.v

2. .1 a pneumatic hammer, the combinav tion of a cylinder,'a piston arranged torecprocate therein, a valve located at the rear end of the cylinder for distributing the fluid pressure to and from opposite ends of the cylinder, a valve box for such-tool having an extension provided with' a suppl passage communicatin with the valve, an a asping handle a apted to be connected with the source of supply and provided with a socket portion adapted to reciprocateupon said extension and to thereby govern its a pneumatic hammer, the combination of a cylinder,-a piston arranged to reciprocate therein, a valve located at the rear end of the cylinder for distributing the fluid pressure to and from opposite ends ofthe cylinder, a valve box for such' tool having an extension provided with a supply pas-- I sage communicating with the valve, and a grasping handle adapted to be connected with the source of 'supply and provided .with a socket portion adapted to reciprocate upon said extension and to thereby govern its supply passage, said socket portion having a passage extending to its front en d for the supply of livev Huid pressure from the source of supply for normally holding vsaid 4 handle outwardly with a' yieldin pressure and thereby cutting oil"l the supp y of fluid pressure to the valve. 4

4. In a pneumatic hammer,the combination of the casing A, the valve block G lo'- cated in lthe rear end thereof and having the rearwardly extending tube I, the cylindrical nut H screwed into the rear end of the casing S, the handle- L havingthe cylindrical extension K surrounding the tube l I between the latter and the nut H and movable longitudinally thereof, said handle being provided with an inlet port N, and the tube I being provided with a port a communicating' vwith the port N when the handle is in vone position, and also with a port Z) opening into the valve chamber, substantially as described.

5. In a pneumatic hammer, the combinal tion of the casing' A, the'valve block G fit-- ting in the rear end thereof and having the rearwardly extending tube I, the nut H screwed into the vrear end of the casing A, the handle L having the forward extension K ysurrounding the tube I within the nut H,

means for holding the handle in place while' permitting slight longitudinal movement of it upon the 'tube I, means for normally ressing the handle rearward thereon to its 'imi't-of movement, an inlet port N in the handle, a port e in thetube U communicating with rthe. port Nl when the handle is in forward pstion, and a port b between thev4 i'terior'of 'the tube' I and the valve chamber, substantially as described.

6. In a pneumatic hammer, the combination of the tube I secured to the body of the tool, the handle L having the extension-K fitting'around and adapted to slide longitudinally upon the tube I, ,a pressure chamber, as P, between the body of the tool and 1 lo the front end of the handle extension K, a port for-I admitting the motive iuid tov such chamber; to'press the handle rearward, and

an inlet "port opened by forward movement of the handle Ato admit motive fiuid to the interior of the tube I and thence to the valve chamber, for the purpose described.

7. In a pneumatic hammer, the combination 'of the tube I secured to the body of 'the tool, the handle L having the forward extension-Kfitting around and ada ted'to slide upon the tube I, an inlet port in the handle L, a plort a in the tube I communieating with t forward position, a vport ZJ between the tube I'and valve chamber, and a port O between the inlet port N and a pressure chamber P at the front end` of the handle extension K,

e port N when the handle is in llll for admitting motive Huid to said chamber to press the handle rearward, substantially as described.

l 8. In a pneumatic hammer, the combination of the casing A, the valve block G fit- Y ting in the rear end thereof and having the rearwardly extending tube I, the nut H screwed into the rear end of the casing A, the handle L having the extension K between the latter and the nut H, the screw ing the longitudinal M passing through the nut H and enterrecess 1n the extension K, the inlet port N in the handle L communicating with the ports a in the tube I communicating with the groove a when the handle is in forward position, the port O between the inlet port N and the chamber P at the front endof the` extension K and the port b between the tube I and-valve chamber, substantially as and forthe purpose described.

9. A pneumatic hammer rovided at its front end with a' tool-receiving bore which opens into the front end of the pistonV chamber 'proper and is adapted to receive and hammer'ha'ving a-piston end is partly closed by surrounding and adapted to slide upon the tube I annular groove a, the.

shoulder surrounding an( opening adapted to receive and make fluid-tight engagement with the collarless cylindrical shank of the removable working tool, and` having a passage for admitting the motive iiuid to the front end of said chamber, whereby the shank of the tool is made to form part of the end wall of the chamber against which themotive fluid acts to drive thepiston rearward.

l1. A pneumatic hammer provided at its front end witha tool-receiving bore which opens into the front end of the piston chamber proper and isadapted toreceive and at such end Wall of the piston closed by the collar-less cylindrical shankv of the slidingly removable chisel or other working tool, a solid piston reciprocating in the piston chamber, and a passage leading or- Ward through the cylinder Wall for admitting the motive iiuid to the front end of the pistonchamber; substantially as and for the purpose described.

12. A pneumatichammerhaving a piston lchamber whose front end is partly closed by an annular shoulder surrounding an opening adapted to receive and make uidtight engagement with the collarless cylindrical shank 'of the slidingly removable working tool, a solid piston reciprocating in the piston chamber, and a passage leading forward through'the cylinder wall for admitting the motive fluid to the front end of said chamber; substantially as and for the purpose described.

WILLIAM F. SCHMIDT. Witnesses -EMIL WENGER, B. VY. TYLER.

chamber be 

